(FORTUNE Magazine) – Wall Street hasn't exactly been pampering Wayne Huizenga lately. The shares of his car-retailing empire, AutoNation, and his garbage hauler, Republic Services, are both chewing gravel. But while his stocks may be going nowhere, the Miami billionaire has been on a tear when it comes to vacation homes. Huizenga sold a shingled cottage on Nantucket for $4.2 million last September, nearly double what he paid in 1997. Across the lane, he's asking a king's ransom for the harborfront Victorian he bought one year ago for $4.2 million. Odds are he'll get nearly his full price--no gasps, please--$14 million.

Huizenga is riding the investment world's newest shooting star, luxury homes in America's elite resorts. Almost anyone who purchased a high-end house in old-line markets like Nantucket or Aspen has watched its price jump by 100% to 150% over the past five years, according to DataQuick, a real estate research firm. If you'd bought in a former backwater that recently sailed into the top echelon--Naples, Fla., say, or Jackson Hole, Wyo.--you could have tripled your money. Alongside those gigantic gains, the 70% return you'd have pocketed from the S&P 500 since 1997 looks pretty puny. People who shifted money from stocks to trophy homes just before equities crashed are crowing. "My wealth would have fallen substantially if I'd left all my money in the market," marvels Jon Koncak, a retired center with the Atlanta Hawks who bought a Jackson Hole ranch in 1998. "But my house appreciated so much that I'm ahead by a couple of million."

What's really amazing is that these resort homes are holding their sumptuous gains even as stocks keep tumbling. Can it last? When equities have plunged in the past, luxury real estate values have generally followed about a year later. But this time may be different. The Napas and Nantuckets of the world are benefiting from two trends: a powerful demographic wave that's swelling the demand for vacation houses, and a dearth of beautiful, buildable land.

The resort market is also attracting a new class of buyers. In the past the wealthy bought houses in Nantucket or Aspen in their early 60s, often as places to retire. Now the baby-boomers are taking charge. Savoring the mountains and beaches while they're still young and working isn't enough; boomers want to own the lakefronts and vineyards and valley views. "It's not just second homes, but third, fourth, and fifth," says Lew Goodkin, a Florida real estate consultant. "We're seeing far more expensive purchases, by far younger people, then ever before."

Despite the high prices, the stock of new homes and subdivisions is growing slowly, for two reasons. First, resorts like Nantucket and Napa are small to begin with. Second, strict environmental laws are removing more and more land from potential development. The result is as predictable as the tides: Relentless, enduring pressure on values for years to come. Right now prices are stable. But in most top resorts, only 3% to 4% of the houses are for sale. That inventory is far too low to create a buyer's market. Within a year or two, prices should start rising again at double-digit rates.

Best of all, making money is just one of the pleasures of owning resort property. FORTUNE examined the boom in four prime markets: one that's long established--Nantucket--and three recent arrivals in the top category, Naples, Napa, and Jackson Hole. In each, owners swore that the biggest return is the exhilaration of owning their private piece of heaven.

NANTUCKET. Sam Lehrman wasn't thinking investment potential when he paid $8.3 million last year for a hilltop cottage on Nantucket Sound--at the time, a record price for the island. What drove Lehrman was pure emotion. "It wasn't an economic decision," says Lehrman, a developer from Washington, D.C. "We fell in love with the property, pure and simple." By following his heart, he also made a good investment. The value of his shingled heirloom has already risen by over $1 million.

Nantucket's cachet is capturing a graceful, bygone era, and stubbornly refusing to change. The town is a near museum that preserves its pedigree as an 18th-century whaling village. Plans for new houses must be approved by a historic commission that requires traditional Quaker houses in the town and old-style, shingled homes in the woods and meadows--no Hamptons-style McMansions, please!

The island keeps a lid on growth by limiting construction to 120 new homes a year. A land trust assesses a 2% tax on all sales, and uses the proceeds to purchase land for open preserves. At least half the island's 50 square miles are exempt from development, and the stock of buildable land shrinks by the month.

Nantucket's retro-chic ambiance is catnip for CEOs--Jack Welch of GE, Larry Bossidy of Honeywell, and Amos Hostetter, former chief of MediaOne, to name a few. The big, busy airport is a major plus; Huizenga and his wife come and go in customized Boeing 727s. But it was a new golf course that enshrined Nantucket as a mecca for the corporate elite. Until the mid-'90s, the island had only one private course, the superexclusive Sankaty Head Golf Club, and even CEOs couldn't get in. But in 1998 the Nantucket Golf Club opened. Corporate chieftains would arrive in their private jets, play a round, then zip home that evening. "It became a big status thing to play there, even if you didn't have a house on the island," says Clarence Doucette, a leading Nantucket broker. By the late '90s, wealthy day-trippers started buying and building multimillion-dollar homes.

The numbers are truly astounding--and are still rising. In 1993 only 17% of home sales brought over $1 million. Last year the figure was 58%. More than a third of the sellers pocketed over $2 million. This year the dreary economy has shrunk the number of sales, but prices remain buoyant: The portion of $2-million-plus sales is now running at over 40%. No place matches Nantucket for molding antiglitz into real estate glamour.

NAPLES. In 1998, J.D. Williamson was racing the clock to find a retirement home in an quietly elegant, warm-weather community. But Charleston or Carmel wouldn't do. The balmy, classy place had to double as a tax haven. Williamson was poised to sell his broadcasting and cellular-phone businesses in Youngstown, Ohio. By moving to a state with no capital gains and income tax, he'd save $6 million on the sale alone. "That's what you call being under the gun to relocate," recalls Williamson. Florida fit the profile for taxes and weather. Instead of picking glitzy Palm Beach, Williamson chose an enclave favored by rich but unvarnished Midwesterners like himself--Naples. "For unpretentious, unaristocratic people from the old economy, this is the place," says Williamson.

Naples has ascended faster in the past five years than any resort in America, rising from a backwater to an A-list address that rivals Palm Beach in prices, if not fame. Naples started gaining cachet in the early '90s, when a new airport 20 miles north in Fort Myers made it far more accessible, and I-75, a highway through the Everglades, brought Naples within a two-hour drive from Miami. But the turning point was the rebirth of downtown Naples. In the mid-'90s, the old shopping district was an eyesore. The city fathers hired renowned urban planner Andres Duany to create a blueprint for an enticing medley of modern and classic Mediterranean architecture. Today, Fifth Avenue, Naples's answer to Palm Beach's Worth Avenue, is a major tourist attraction--a blend of swank restaurants and boutiques.

The downtown renaissance brought new luster to the area around it, Old Naples, the traditional neighborhood that boasted waterfront property. Suddenly, the combination of beachfront living and a charming village center made Old Naples incredibly hot. The frenzy is strongest in Port Royal, a community of 700 houses where the average sale has almost doubled, to $3.8 million, since 1997. For premier properties, the gains are greater. This year a local attorney received a knock on his door from a stranger who needed a place to stay while he built a house nearby. In the end the visitor offered $10.5 million for the attorney's home--$7 million more than the lawyer had paid to buy the land and build the house. He sold.

Naples also boasts a panoply of gated, golf course communities, where big homes fetch $5 million or $6 million. But as in most resorts, the higgest prices--and the best potential for appreciation--rest with waterfront property. Unlike lots on the 16th hole, they're not making many more spaces on the beaches or bays. That's why Williamson bought in Port Royal. He grabbed not just waterfront, but also what Naples residents call "good water." That's a combination of wide canal frontage and expansive vistas. His house is a 7,000-square-foot Tuscan-style wonder with a movie theater, Italian marble floors, and a four-tiered pool with cascading fountains, not to mention a pond for exotic Japanese koi fish. The $11 million price doesn't faze him. The house is probably worth $1 million more than he paid early last year. And hey, where else can you buy that kind of luxury with the bundle you save on taxes?

NAPA. What water is to Naples, vineyards are to Napa Valley. In Napa, the talk, the parties, the friendships--everything--revolve around winemaking. For wealthy vacationers and retirees, nothing confers higher status than owning your own rows of grapes. A passion for wine is also proving an excellent investment for Bob and Dottie Mulholland, the husband-and-wife team who head the Gap's shoe division in San Francisco. In 1998 the couple decided to take what it would cost to acquire a small San Francisco townhouse and buy property in the Napa Valley instead.

At first Bob Mulholland played Mr. Blandings, Napa-style. The Mulhollands paid $800,000 for 20 acres on the flat, green valley floor, equipped with a cheap, Tudor-travesty house with a rotting roof and a swampy "duck pond" that bred mosquitoes. But the property had what they coveted: a vineyard. The Mulhollands built an airy, rust-colored Florentine villa for $1.2 million. They ripped out the old vines and planted 17.5 acres of merlot and chardonnay at a cost of $300,000. They now sell their grapes to Miner Family Vineyards, one of the region's best boutique wineries, for $200,000 a year, about $140,000 more than the cost of harvesting the grapes. "The wine bug really caught us," says Bob. Oh, and his $2.3 million investment is now worth around $8 million. Grins Bob: "We won the lottery with this one."

The Valley runs 26 miles from Napa to Calistoga, framed on both sides by sunbaked mountains. It's America's biggest and best wine-growing region; dotting the Valley floor are famous vineyards like Staggs Leap, Rutherford, and Mondavi. "Until nine months ago the dot-commers who caught wine fever were driving up prices," says Pat Taylor, a broker with Morgan Lane Real Estate. Now, says Taylor, wealthy baby-boomers are stepping into the breach.

Even in the sour economy, it's unlikely prices will tumble. The Valley offers little empty land for new vineyards. Buyers want to plant grapes and erect grand houses on what's left, the hillsides. But new environmental rules place severe restrictions on mountain vineyards. So wine mavens like the Mulhollands will control an increasingly rare and valuable commodity. If life's not a beach, it's a vineyard.

JACKSON HOLE. "I can look out my window and see elk from Harrison Ford's farm grazing on my property," marvels Jon Koncak, the retired NBA center who lives in Jackson Hole. Koncak moved here for the classic reasons: He relishes the rugged, outdoor lifestyle and ample tax benefits--Wyoming, like Florida, has no income tax. Koncak skis in the winter on jagged Teton Mountain, and in the summer he and his wife, Darlene, fish for trout in the Snake River, ride appaloosas, and hike in Yellowstone Park. "It's the feeling of wildness that's irresistible," he says.

In the past five years Jackson Hole's status as a versatile, year-round playground has created a huge luxury-home market bathed in the area's rustic, even cornball style. The architecture of choice is log-cabin chic. Luxury log homes--carpenters hand-peel the logs before construction--cost $300 a square foot to build. The sudden spike in prices rivals Naples. In 1996 a big house on five acres in the tony John Dodge development sold for around $1.7 million. Today the price is $3.5 million. The priciest homes sell fully furnished, with cowboy bronzes and Indian rugs; typical price for the contents: $500,000.

But Jackson Hole lacks the proximity to big cities that helps protect Nantucket and Napa, so it's more sensitive to the slowing economy. Hence, prices peaked in late 1999. Since then the $3.5 million house in John Dodge has barely budged in value. Still, it's unlikely prices will drop. Only about 4% of the area's luxury housing stock is for sale. That's not enough inventory to create a rash of bargains.

And buildable land is scarce. Rather than battle environmentalists to create large subdivisions, ranchers are selling a few huge lots, then sheltering the proceeds with big tax deductions by leaving most of the land in agriculture. That's how Koncak bought his property. In 1998 he acquired 38 acres for $1.5 million, added $500,000 in landscaping, and built a cedar-plank house and barns for around $3.3 million. Three years later Koncak's $5.3 million investment is worth about $10 million--that's a slam dunk even an ex-NBA player can appreciate.